the stuff rocks are made of Minerals the stuff rocks are made of

Composition of Minerals Element – substance that cannot be broken down into simpler substances by chemical or physical means. 112 are known (95 naturally occurring)

Composition of Minerals Atoms – Smallest particles of matter that contain the characteristics of an element. Atomic structure

Composition of Minerals Chemical bonding – formation of a compound by combining two or more elements. 1. Ionic bonding - Atoms gain or lose outermost (valence) electrons to form ions Example: Halite (NaCl)

Composition of Minerals 2. Covalent bonding Atoms share electrons to achieve electrical neutrality Example: Water (H2O) Silicon dioxide (SiO2) H2O Quartz

Composition of Minerals 3. Metallic bonding Valence electrons are free to migrate among atoms Weaker and less common than ionic or covalent bonds Bronze Age tools 5,000 YBP

So, how small is an atom? Composition of Minerals https://www.ted.com/talks/just_how_small_is_an_atom 5:30

Unit 6 Minerals Objectives: Describe five characteristics of minerals Describe process of mineral formation Classify minerals (silicates, carbonates, oxides) Use physical and chemical properties to identify minerals Feldspar Fluorite Muscovite (mica)

Unit 6 Minerals Mineral – a natural occurring, inorganic solid with an orderly crystalline structure and a definite chemical composition Inorganic = not consisting or deriving from living matter

I. Five Characteristics of Minerals Naturally occurring Solid Substance Ordered crystalline structure Definite chemical composition Generally considered inorganic

Sugar vs Salt

II. Rocks vs Minerals Rocks are made of one or more mineral(s) Most rocks occur as aggregates of several different minerals. Aggregate = minerals are joined in a way such that their individual properties are retained Example: Granite rock = Quartz, Feldspar, Hornblende, Muscovite (mica) Minerals are rocks, but they are made of only one type of mineral All minerals are rocks, but not all rocks are minerals

II. Rocks vs Minerals How many minerals are there? There are over 4000 known minerals Only 100 minerals are considered common

III. Mineral Formation a. Crystallization from Magma Slower cooling magma = bigger crystals Faster cooling magma = smaller crystals Examples: Feldspar, quartz, muscovite (mica), hornblende

Cueva de los Cristales (Cave of the Crystals) Mexico https://www.youtube.com/watch?v=laMZAJ2L_1Y 10:00 https://www.youtube.com/watch?v=tlz8Z_QZU40 10:00

III. Mineral Formation Halite Calcite b. Precipitation – dissolved substances reacting to form minerals when water evaporates Examples: Halite and Calcite Halite Calcite

III. Mineral Formation c. Pressure and Temperature – when existing minerals are subjected to changes that might cause them to recrystallize while still solid under pressure. Examples: talc

III. Mineral Formation d. Hydrothermal Solutions – very hot mixture of water and dissolved substances Example: Bornite (peacock ore), quartz, pyrite (iron sulfide)

III. Mineral Formation d. Hydrothermal Solutions – very hot mixture of water and dissolved substances Example: Gypsum Crystals

IV. Classification of Minerals a. Silicates – silicon and oxygen combine to form a single structure quartz SiO4

IV. Classification of Minerals b. Carbonates – minerals that contain the element carbon, oxygen, and one or more other metallic elements Calcite CaCO3

IV. Classification of Minerals c. Oxides – minerals that contain oxygen and one or more other elements, usually metals Hematite Fe2O3 Pyrolusite

IV. Classification of Minerals d. Sulfates & Sulfides – minerals that contain the element sulfur Pyrite FeS2

IV. Classification of Minerals e. Halides (Halogens) – minerals containing a halogen ion and one or more other element(s) Fluorite CaF2

IV. Classification of Minerals f. Native Elements – minerals that contain only one type of element Gold, Silver, Lead, Sulfur

V. Mineral Identification a. All minerals have observable/measurable characteristics called properties

V. Mineral Identification 1. Color Color is the most obvious property of a mineral Unfortunately color is the least reliable property - Slight impurities in a mineral can change the color

V. Mineral Identification Streak The color of the powder left behind on a white tile is the mineral's streak.

V. Mineral Identification Luster The luster of a mineral is the way its surface reflects light There are two main categories of luster Metallic: shines like a piece of metal Nonmetallic: does not look like metal Mineral of the same type may have the different luster (hematite)

V. Mineral Identification Hardness The ease or difficulty with which a mineral can be scratched Diamonds are the hardest naturally occurring substance known The Mohs Scale of Hardness is use to rate the hardness of minerals

Mohs Scale of Hardness

V. Mineral Identification Cleavage Planes Cleavage planes - when minerals break along flat, smooth, parallel surfaces (planes)

Cleavage Planes Cleavage planes form when there are weaknesses between layers of atoms

V. Mineral Identification Types of Cleavage Count the number of parallel planes

V. Mineral Identification Fracture When breakage occurs on irregular surfaces

Special Properties Magnetism – some minerals are magnetic Taste – some minerals have a distinctive taste Reaction with dilute hydrochloric acid – some minerals fizz when a drop of acid is placed on them